JP Morgan's Kolanovic warns that the S & P 500 will plunge 23% by the end of the year.

The S & P 500 could hit new highs, but JPMorgan's Marko Kolanovic said the index could fall in the coming months amid headwinds such as a slowing economy and lower earnings revisions. The chief market strategist at JPMorgan and his team said in their mid-year outlook on Friday that the index was set to fall to 4,200 by the end of the year, down about 23 percent from Thursday's close of 5,483. After the release of the core PCE index, the index broke through the 5,500 mark in early trading on Friday. Kolanovic's view was essentially a reaffirmation of his more than year-old forecast, even as other Wall Street institutions raised their point forecasts for the index to keep up with the broader market's surge.